Newly ground cutting tools, such as drill bits, often have cutting edges that are very sharp which tend to rapidly wear and/or weaken at the tips leading to failure. Honing or polishing is a final finishing operation conducted on cutting tools. Honing or polishing is a surface finish operation, not a gross geometry modifying operation.
As used herein, “finishing” may include polishing and honing. As used herein, “polishing” refers to the act of removing irregularities from the surface of a part. As used herein, “honing” refers to the rounding of a cutting edge to strengthen and smooth the edge surface.
Many drill bit finishing operations utilize brushes or abrasive stones to finish the bits. These processes take many steps to complete and are generally inefficient and expensive. Moreover, brush and stone processes are not well suited to produce precision instruments.
In response to these deficiencies, other finishing methods have evolved including abrasive fluid sprays, electrochemical deburring methods and tumbling techniques. However, most of these methods are either time consuming and expensive, difficult to perform and control, or fail to ensure consistent and repeatable results.
Abrasive flow machining (AFM) is a well known nontraditional machining process whereby a visco-elastic medium, permeated with an abrasive grit, is extruded through or past a workpiece surface to affect an abrasive working of that surface. The abrasive action in abrasive flow machining can be thought of as analogous to a filing, grinding, lapping or honing operation where an extruded visco-elastic abrasive medium passes through or past the workpiece as a “plug.” The plug then becomes a self forming file, grinding stone or lap as it is extruded under pressure through the confined passageway restricting its flow, thereby working the selected surfaces of the workpiece. The typical AFM process (two-way flow) uses two vertically opposed cylinders which extrude an abrasive media back and forth through passages formed by the workpiece and tooling. Abrasive action occurs wherever the media enters and passes through the most restrictive passages. The extrusion pressure is controlled, as well as the displacement per stroke and the number of reciprocating cycles.
One-way AFM systems use a cylinder to flow the abrasive media through the workpiece in only one direction, allowing the media to exit freely from the part for fast processing, easy cleaning and simple quick-exchange tooling.
The present invention has been developed in view of the foregoing.